Lubricating system



Patented Nev." 19,, 1935 UNITED STATES:

PATENT orries 2,021.32 V nunnrcsrnva srs'rm Application September 1:,1024'. Serial No. mus: .3 Claims. (01. lea-r96) This invention relatesto lubricating systems for aircraft power plants, and is particularlyconcerned with improvements in apparatus for controlling the'temperature of lubricating. oil.

In the conventional aircraft power plant installation, the engine isprovided with a force feed lubricating system including one or morepumps, and oiliscarriedinaseparatetankthe tank being connected to theengine by one pipe which permits oil to flow from the engine to thetank, and by another pipe which permits oil to flow from the tank to theengine. In engine operation, the oil becomes heated, and suitable oilcoolins radiators are placed in series with onset the other of the oilpipes. Means have been'proe. vided in the past for controlling the airflow through the oil radiator or for controlling the oil flowtherethrough, in order that the lubricating oil may be maintained atdesirable temperatures. Likewise, means have been provided in the oiltank to permit of a rapid warming up of a small portion of the 011 inthe tank, after which the main body of-oil in the tank may he warmed atleisure. This invention provides thermostatic means for controlling oiltemperature, both with respect to the air flow through the oilradiator,"

or with respect. to the amount of oilwhich is permitted to actively flowthrough the tank.

An object of the invention is to provide an im-' proved 'means forcontrolling luhricating oil temperature's in aircraft power plantinstallation.

A further object is'to provide an automatic illzlermostatic means forregulating oil te'mpera- Another object is to provide an improved oiltank construction permitting of automatic oil temperature control.

A still further object is to'provide a thermostatic device inconjunction with a lubricating system, in an aircraft power plant.

For further objects, reference may be made to the annexed specificationand to the drawings, in which: I T

Fig. 1 is a side elevation, partly broken away: of the forward portionof an aircraft showing a lubricating oil circuit embodying'thisinvention;

Fig. 2 is an enlarged fragmentary section through an aircraft oil tankembodying the 'device of this invention;

Fig. 3 is a section on the line 3-3 of Fig.2:

Fig. 4 is a section on-the line H of Fig. 2;

Fig. 5 is a fragmentary side elevation, partly broken away. showing analternatlve'emhodiment of the invention: and v Pig. 6 is anenlargedsection,=,through the al-, ternative oil temperature controlapparatus.

In Fig. 1," ll designates-the-forward'portion ofan airplane-fuselagecarrying anen'sine Ii of theradial'cylindertype, ,the cylinders being. 5

surrounded by a low drag-cowling i2. The engine shaft carriesa propellerii at its forward end.- A'n'oil tank I ismountedinthe fuselage II, andis provided'with an upper oil inlet connection "communicating by meansof a conduit I 10 with an oil cooling radiatoril. The radiator i| in"turn, communicates with the outlet side of a seavensins oil pump carriedwithin theensi e ii,

by means of a conduit I. The suction side of the oil pressurepumpmounte'd in the engine cas- 1s ing is connected to a conduit I 9communicating.

, through a valve in with an oil outlet connection flat the bottom ofthe oil tank It. #The valve 10 is'prov'id'ed with a drain pipe 22 and,by means of thevalve, the lubricating system may hem drained. Theconstruction of the tank I4 is shown in'detail in Figs 3 and 4,- thetank comprisinga casing 23 of any preferred shape,vhaving a boss 24 onits upper surface, this-boss pro-1 d s an penlnsadapted to be covered bya plate 25. The plate is attached by screws 1' to the boss 2. The plateis providedwith a threaded opening 21 within which the connection I! isadapted to bescrewed. An annular flange 28' extends inwardly from theplate and serves 30 as a locating means for the upperend -of a tuhu larsleeve 20, the lower end of the sleeve being located in an annularflange Slformed as part of a boss 3| fixed to the bottom of the tank.Be-

tween the flange 30 and thebossjl are a plurality of openings '32. Tothe boss 3|, a cup 31 is attached by screws 80, the. cup at its lowerend having a threaded opening 35 within which the. connection 2| may bescrewed. A plurality of radial openings 36 are formed in the upperportion of the sleeve 2!, and a plurality of openings 81 are formed inthe lower end thereof.

A baiile 38 is attached within the upper end of thesleeve 29, above theopenings I6, this baifle, having cut away portions 39, to permit oilenter- 5 ing from the connection 21 to flow past the balls anddownwardly within the sleeve 29. Inter- Y mediatethe openings 36 and 31,a butterfly valve 4m pivoted, this valve being capable of movement to aposition wherein the sleeve is suhfl stantially closed, or to a positionwhere the sleeve is open. A link ll connects the valve 40 with a pin 42carried on a flexible diaphragm 43, the.

diaphragm-being sealed within a casing 44.

murals introduced between the j,

and the casing, this fluid preferably having a rather high coeflicientof expansion. Thereby, upon cooling of the fluid within the casing 44,it will contract to effect opening of the valve 40. Conversely, uponwarming of the fluidwithin the casing 44, the fiuid will expand toeffect closing of the valve 40.

The operation of the oil tank is as follows: Assuming the engine and oilto be cold, starting of the engine will immediately start circulation ofthe oil therein and oil will be passed through the conduit l6, throughthe connection 21, and into the tank. By virtue of the oil in the tankbeing cold, the valve 40 will be open, and the oil will most readilyflow downwardly through the sleeve 29, out through the openings 31,thence through the openings 32, and backto the engine through theconnection 35 and the conduit l9.

As the engine continues to operate, theoil will become warmed, and. inpassing by the casing 44 will warm the thermostatic elements therein toeffect closure of the valve 40. Such closure will tend to prevent flowof oil through the sleeve 29, causing the oil entering the tank to flowinto the main body of the tank through the openings 36. Oil drawn fromthe tank will then necessarily flow from the main body of the tank,through the openings 32 and back to the engine.

The organization shown is particularly useful in cold weather operationas it expedites the warming up of the engine by re-circulating, atfirst, only a small quantity of oil. The heat from the oil passingthrough the sleeve 29 tends to warm up that oil surrounding the sleevewhile permitting operation of the engine at full power with the .smallamount of quickly warmed Automatically, as the oil is warmed and isrendered sufliciently fluid, the oil in the main body of the tank ispermitted to circulate through the engine, preventing the overheating ofthat small quantity of oil which circulated when the engine was firststarted.

In conjunction with the ofl cooler I'I, an adequate temperature controlfor the oil is accomplished in warm or cold weather. It will be observedthat the full quantity of oil circulating through the engine is passedthrough the, cooler, the cooler being normally designed to take care ofthe maximum cooling conditions which may be encountered in service.Over-cooling of the oil being circulated is prevented, however, sincethe valve organization in the tank will automatically cause the oil flowfrom the tank to be govof thermostatic oil temperature control whereinthe tank I4 is of conventional type. In this embodiment, conduits 5.0and 54 provideoutlets from the tank to the engine, and between theseconduits is a thermostatic device 5lhaving a connection with a shutter52 controlling air flow through the oil radiator II. The oilradiator I1is, as before, connected by means of conduits l8 and IS with the engineH and with the tank It, respectively. The device 5| comprises a cup 53communicating through'the conduit 50 with the I tank and through theconduit 54 with the engine.

Within the cup, a flexible diaphragm element 55 is enclosed in a casing55, the space between the two being filled with a fluid having a highcoefficient of expansion. The diaphragm is con- 5 nected by a pin 51with a bell crank 58 pivoted at 59 to the cup .53, the arm Goof the bellcrank being connected by a link 5| with the oil radiator shutter 52. Theelements 55 to 60, inclusive, may beconveniently carried on a coverplate 52 10 adapted to be screwed to the open side of the cup 53 bymeans of screws 63. Adjustment of the mechanism may be effected byascrew connection 64 in the link 6| whereby the proper degree of openingof the shutter 52 may be determined with reference to the action of thethermostat comprised by .the elements 55 and '56. It will be seen thatoil entering the engine from the tank It will all pass through thethermostatic device 5|, which in turn will control the degree of coolingimposed upon the oil leaving the engine on its way to the tank I l.-

The oil radiator ll, though not shown in detail, is of conventional andwell known construction comprising a nest of honeycomb tubes containedwithin a casing, the oil being adapted to circulate between the tubes,and the cooling air being adapted to pass through the tubes. If it isdeemed desirable, the devices shown in Figs. 1 to 4, inclusive, andthose shown in Figs. 5 and 6 may be used in combination on a singleinstallation to attain a still finer degree of oil tempera- 'turecontrol. Similarly, a single thermostatic unit could readily be utilizedto control air flow through the oil radiator l1, and to simultaneouslycontrol the valve 40 which controls the flow of oil within the oil tankshown in the first four fingers.

While I have described my invention in detail in its present preferredembodiment, it will be 40 obvious to those skilled in the art, afterunderstanding my invention, that various-changes and modifications maybe made therein without, departing from the spirit or scope thereof. Iaim in the appended claims to cover all such modi- 5 ficationsandchanges.

What is claimed is: I r

1. In an aircraft power plant installation including a. heat generatingengine, an oil tank having an inlet conduit through which oil passes 50from said engine to said tank, an exit conduit through which oil passesfrom said tank to said engine. an enlarged perforate conduit within saidtank with the ends of which said inlet and exit conduits-respectivelycommunicate, a thermostat device immersed in the oil adjacent saidexitconduit, and a valve operated by said thermostat for opening and closingsaid perforate conduit.

2. In an aircraft power plant installation ineluding an engine, alubricating oil tank therefor, 60 inlet and outlet conduits to and fromsaid tank connected with said engine, said inlet conduit e g said tanksubstantially at the top thereof and said outlet conduit entering saidtank substantially at the bottom thereof, a tubular sleeve 65 connectedat its ends with said conduits, said sleeve having openings adjacent theends there- .of for communication with the interior of said tank, avalve in said sleeve intermediate said sleeve openings, and a athermostatic device in intimate 7 contact with the oil for operatingsaid valve.

3. In an oil tank for use with an aircraft power plant and having spacedinlet and out et connections, means for directing the oil flow throughsaid tank directly'from said inlet to said outlet 7 some connection, andmeans responsive to change in temperature 0! the circulating oil fordirecting the oililow throughthemainbcdyotsaidtanh 4. In an oil tank foruse with an aircraft power plant and having spaced inlet and outletcornice-- tions, means within said tank for causing circulation of oilin a direct path between said oonnections. and thermostaticallycontrolled means responsive to oil temperature for diverting oilcirculation from said direct path to an indirect with through the bodyoi said tank.

5. A lubricating oil tank for aircraft having-a top inlet connection, anannular flange-extending inwardly from the tank body and encircling saidconnection, said tankhaving an opening opposite said inlet connection. asleeve having perforations, insertable through-said opening forengagement with said flange. and a fitting carry ing an outletconnection adapted to be attached to said tank over said opening iorholding said sleeve within said tank.

6. A lubricating oil "tank for aircraft having a: top inlet connection,an annular flange extending inwardly from the tank body and encirclingsaid connection, said tank having an opening opposite said inletconnection, a sleeve having pertorations,insertablethrouglisaidmningiormment with said fiange, a fitting carrying an outlet connection adaptedto be attached to said tank oversaid opening tor holding said sleevewitlnnsaidtanhavaivewitbinsaidsleeveyand a thermostat mounting in saidfitting tor-operatins said valve.

'1. In an oil tank for a power plant, meansdividing said tank into twocents, an inlet and an outlet for said tank, said means having isopenings to permit the interilow of oil between said compartments. andthermostatically con-' trolled means responsive to the oil temperaturetor-closing one said compartment to the passage. of oil therethroughfromv said inlet to said outlet. is

8. In a tank. having a restricted fluid conduit therewithin, saidconduit defining outer and inner fiuid containing compartments, saidconduit-having openings to. permit the ilow or fluid between saidcompartments, an inlet and an outlet for said so tank, and a'fiuidtemperature responsive valve for closing said inner comparhnent. uponclosure oi'whiohthecontainedfiuid istofiow tin-0118 said outercompartment in its 0 from saidinlettosaidoutlet. b

